1. Field of the Invention
The present invention relates to a nozzle hole sealing device for an injection nozzle, which is located between a nozzle of an injection molding machine and a tool used by a robot which is combined with the injection molding machine.
2. Description of the Related Art
In a highly automated injection molding system, a robot is combined with an injection molding machine to let it perform the change of core, the unloading of a product, and the opening/closing of a gate. For this purpose, various tools are made available, and changed by attaching to and detaching from the wrist of an arm end of the robot.
On the other hand, the injection molding machine undergoes a purging process when changing a resin or color. In order for the purging to be performed efficiently by changing the resin all over the screw, however, it is preferable to initially seal the nozzle hole at the nozzle tip, apply a back pressure on the screw, and perform the measuring operation for purging while increasing the resin density. Conventionally, however, a tool for a robot designed for use in blocking the nozzle hole at the nozzle tip of injection molding machine in purging has not been available. Therefore, something like a shutter used to be placed between the fixing platen and the nozzle (Japanese Unexamined Patent Publication No. S63-185617), or a shut-off nozzle has been used. Those methods, however, have some limitations such that the space for placing the blocking tool and that the usable resins are limited. Moreover despite the fact that a robot is capable of performing various works, a separate device is needed only for purging to entail an extra cost.